On a modern SSD however, this problem is largely solved. Since the partitions exist on the same physical drive, there can be access contention. The downside of using partitions compared to using multiple physical drives, is that there’s a performance penalty. There are more uses for partitions besides this, but those are the most important ones. For example, most laptops have a protected partition on the main system drive that contains software and data which can restore the machine back to its factory default. Partitions are also used for recovery purposes.
